Ship project history: In days of the First World War in the USA the big
number of 110ft submarine chasers has been built. Secretary of Navy Roosevelt (future
President) participated in development of building of this huge series on small
shipyards. When in 1937 leading particulars of ASW ship intended for patrol in
coastal areas and on fleet anchoring were defined, Roosevelt has insisted on return to project of twenty years' prescription, which
at building was criticised for the small displacement and insufficient
endurance. Perhaps, unique concessions for technical progress were a choice of diesels as
main engines and installation of sonar.

Under the
FY1938 program three experimental chasers under some differing projects (SC449, SC450 and SC453)
were built. Latter, designed by the Navy, also has formed a basis for serial
chasers. She differed from the predecessor of WWI times in the increased breadth and stronger hull structure with application of steel
bracings.

Serial SCs were developed from SC453.
Chasers of different years of building differed by armament structure. Only some
lead boats received designed armament, since 1942 DCT "Mousetrap"
was fitted, and 12.7mm MGs were replaced by 20mm Oerlikons; since 1943
newly built ships instead of out-of-date 76mm/23 gun received 76mm/50, and
ASW armament was strengthened by two DCTs. In 1944
replacement of 76mm/23 guns by 40mm "Boforses" started and by next year in
the US Navy only 4 chasers old short gun were remained.

Shortages of diesels of eligible
power led to that 231 chasers received 500hp diesels instead of 1200hp. Maximal
speed of such boats was limited by 16kts.

In 1944 eight hunters
were converted to motor gunboats for operations against Japanese boats
and had index PGM. After rearming their armament consisted from single 76mm/23
gun and single 40mm/56 Bofors or 2 single 40mm/56 Boforses; 4 twin 12.7mm MGs, 1
single 60mm mortar and multi-barrelled 83mm Bazooka.

In 1944 35
SCswere converted to command and control ships of
amphibious forces SC(C).

Modernizations: 1942, earlier
SC497 class chasers
were re-armed as new built ones.

1942 -1943, earlier SC497 class chasers were re-armed as new
built ones.